Added comments to persistence code

server/src/persistence/character.rs

@@ -54,7 +54,10 @@ struct CharacterContainers {
 /// Load the inventory/loadout
 ///
 /// Loading is done recursively to ensure that each is topologically sorted in
-/// the sense required by convert_inventory_from_database_items
+/// the sense required by convert_inventory_from_database_items.
+///
+/// For items with components, the parent item must sorted so that its
+/// components are after the parent item.
 pub fn load_items(connection: &Connection, root: i64) -> Result<Vec<Item>, PersistenceError> {
     let mut stmt = connection.prepare_cached(
         "

server/src/persistence/character/conversions.rs

@@ -276,6 +276,10 @@ where
     // First checks if item is a component, if it is, tries to get a mutable
     // reference to itself by getting a mutable reference to the item that is its
     // parent
+    //
+    // It is safe to directly index into `inventory_items` with `index` as the
+    // parent item of a component is loaded before its components, therefore the
+    // index of a parent item should exist when loading the component.
     let parent_id = inventory_items[index].parent_container_item_id;
     if inventory_items[index].position.contains("component_") {
         if let Some(parent) = item_indices.get(&parent_id).map(move |i| {
@@ -344,6 +348,9 @@ pub fn convert_inventory_from_database_items(
     let mut inventory = Inventory::new_with_loadout(loadout);
     let mut item_indices = HashMap::new();
 
+    // In order to items with components to properly load, it is important that this
+    // item iteration occurs in order so that any modular items are loaded before
+    // its components.
     for (i, db_item) in inventory_items.iter().enumerate() {
         item_indices.insert(db_item.item_id, i);
 
@@ -442,6 +449,9 @@ pub fn convert_loadout_from_database_items(
     let mut loadout = loadout_builder.build();
     let mut item_indices = HashMap::new();
 
+    // In order to items with components to properly load, it is important that this
+    // item iteration occurs in order so that any modular items are loaded before
+    // its components.
     for (i, db_item) in database_items.iter().enumerate() {
         item_indices.insert(db_item.item_id, i);